What are the differences between functors and promises?

What are the differences between functors and promises?

Functors are a design pattern used in functional programming to apply a function to a wrapped value, while promises are used for handling asynchronous operations. Functors allow you to map functions over values, whereas promises represent a value that may be available now, or in the future, or never.

Can you give me an example of a functor?

Sure! In JavaScript, an array can be considered a functor. You can use the map method to apply a function to each element in the array, transforming it into a new array.

And how about a promise example?

A promise in JavaScript can be created using the Promise constructor. For example: let myPromise = new Promise((resolve, reject) => { /* async operation */ }); You can then use .then() to handle the resolved value.

Are there any similarities between them?

Yes, both functors and promises can be seen as containers that hold values. They both provide a way to apply functions to those values, but they serve different purposes in programming.